Method and device for controlling the drive train of a motor vehicle during gearshift operations

ABSTRACT

A coordinated control of a drive train during a gear shift is described. The core of the control lies in establishing an optimal system trajectory for the states of the internal combustion engine and the clutch for the shift operation and in supplying this trajectory to a subordinate control and regulation. Here, the determination of the optimal system trajectory occurs as a function of the stipulations of a higher-order system for controlling the drive train. In particular, it is provided for the optimal system trajectory to be adapted to the driving situation, the driver type, the operating conditions of the assemblies, and the state of the assemblies themselves. Here, the determination of the optimal system trajectory occurs via a real-time optimization algorithm that is executed during driving operation. In this manner, optimal shift operation is attained under all operating conditions that unites a high degree of comfort with a low loss of traction.

FIELD OF THE INVENTION

The present invention relates to a method and device for controlling thedrive train of a motor vehicle during gear shift operations.

BACKGROUND INFORMATION

In vehicles having an automated gear box and an electronically actuatedclutch, an automated gear change occurs by triggering the internalcombustion engine, clutch, and transmission components. These componentsmust be actuated appropriately such that the gear change occurs asquickly and therefore as comfortably as possible.

Conventional methods for determining the target transmission gear which,besides the direct input variables, also take into account the drivingsituation, the driver type, and operating conditions when determiningthe gear. These methods are described in, for example, German PublishedPatent Application No. 196 25 935 or German Published Patent ApplicationNo. 197 03 863.

Moreover, systems for coordinated drive train control are conventional.German Published Patent Application No. 199 37 455 describes a systemfor controlling the assemblies in gear shift operations that is embeddedin a system for controlling the drive train.

However, the conventional methods do not guarantee an optimal control ofthe shift operation with regard to traction and comfort while takinginto account the driving situation, driver type, and operatingconditions.

An object of the present invention is to provide an optimal control ofthe assemblies of the drive train during gear shift operations withregard to traction and comfort under all operating conditions.

SUMMARY

As described above, the present invention relates to the coordinatedcontrol of the elements servo clutch, vehicle engine, and transmissionarranged in the drive train of a motor vehicle during a change in thegear ratio. In accordance with the present invention, temporalprogressions of the states of the vehicle engine and the servo clutchmay be established for the change in gear ratio. The control of theservo clutch and the vehicle engine during the change in gear ratio thenmay occur in such a manner that the servo clutch and the vehicle engineassume the states according to the established temporal progressions.

Thus, according to the present invention, an optimal system trajectoryfor the shift operation may be determined for the conditions of theinternal combustion engine and the clutch and this trajectory may besupplied to a subordinate control and regulation. The determination ofthe optimal system trajectory may occur in this connection as a functionof the stipulations of a higher-order system for controlling the drivetrain.

According to an example embodiment of the present invention, provisionis made that, during driving operation of the vehicle, at least

one driver type value representative of the behavior of the driver ofthe vehicle and/or

one driving situation value representative of the instantaneous drivingsituation and/or

one operating state value representative of the operating state of atleast one element of the drive train and/or

one operating condition value representative of at least one operatingcondition of at least one element of the drive train is calculated. Thetemporal progressions may then be determined dependent upon at least oneof the calculated values. Thus, it may also be provided according to thepresent invention for the optimal system trajectory to be adapted to thedriving situation, driver type, operating conditions of the assembliesand the state of the assemblies themselves.

The determination of the optimal system trajectory may occur via areal-time optimization algorithm that may be executed during drivingoperation. This means that the temporal progressions may be calculatedand updated during driving operation. At the beginning of a change inthe gear ratio, the respective updated progressions may then beestablished as the progressions according to which the control of theservo clutch and of the vehicle engine occurs during the change in thegear ratio.

In particular, a result of this algorithm may include the targetprogression of the engine speed and the target progression of the clutchoutput torque. This means that the output speed of the vehicle enginemay be set as the state of the vehicle engine and the output torque ofthe servo clutch may be set as the state of the servo clutch.

Using the present invention, optimal shift operation may be attainedunder all operating conditions that may provide a high degree of comfortwith a low loss of traction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic top view of the present invention.

FIG. 2 illustrates the present invention embedded in a system forcontrolling the drive train.

FIG. 3 illustrates details of the shifting coordination.

FIGS. 4a and 4 b illustrate examples of the calculation according to thepresent invention of the temporal progressions.

FIGS. 5a and 5 b illustrate examples of the calculation according to thepresent invention of the temporal progressions.

DETAILED DESCRIPTION

The invention is be described below with reference to exampleembodiments.

Using a drive train control, in a vehicle with an automated gear box(AGB) and electronically actuated clutch, the change of gears occurs viacoordinator 111 of the components engine, clutch, and transmission. FIG.1 illustrates the system architecture of the drive train control.

The driving torque desired by the driver is calculated by coordinator111 as a function of relative position hfp of accelerator 110 andtransmission output speed n_ga proportional to the vehicle speed. Outputengine torque md_ma_soll or the setting of an engine speed n_m_soll isrequested by engine control 101 a. Clutch control 103 a is requested toadjust the clutch in such a manner that it is able to transfer a torquemd_ka_soll. Alternatively, it is also possible for the stipulation of atarget position or target force of the actuator that actuates automatedclutch 103 to be provided.

Transmission control device 105 ais requested by coordinator 111 to settarget transmission gear g_soll.

Using appropriate sensors 102, 104, and 106, engine speed n_m,transmission input speed n_ge, and transmission output speed n_ga aredetermined and provided to coordinator 111. Moreover, control components101 a, 103 a, and 105 a provide further signals to coordinator 111 thatwill be clarified in conjunction with the functional structure of thedrive train control.

FIG. 2 illustrates the present invention embedded in a system forcontrolling the drive train. As a function of the position ofaccelerator hpf and transmission output speed n_ga proportional to thevehicle speed, vehicle coordinator 201 determines target drive powermd_an_soll. This target drive performance is converted by drivecoordinator 202 by triggering the assemblies engine 101, clutch 103, andtransmission 105. For this purpose, it provides target engine outputtorque md_ma_soll and target engine speed n_m_soll to engine control203. Drive coordinator 202 also provides torque md_ka_soll to clutchcontrol 204, which clutch 103 may be able to transmit. Target gearg_soll is specified by transmission control 205.

A driver (engine driver 2021, clutch driver 2022, transmission driver2023) is assigned to each of assemblies 101, 103, and 105 within drivecoordinator 202. The coordinated actuation of assemblies 101, 103, and105 during gear shift operations is performed by shift manager 2024,which is part of drive coordinator 202 and provides target variables todrivers 2021, 2022, and 2023 during shifting. Shift manager 2024requests a target clutch input torque md_ke_soll and/or a target enginespeed n_m_soll from engine driver 2021. Shift manager 2024 also requeststhe setting of a clutch torque md_ka_soll from clutch driver 2022 and isable to request a shifting prohibition from transmission driver 2023.

Within shift manager 2024, an engine/clutch regulator 20244 ensurescoordinated control and regulation of engine 101 and clutch 102. Itreceives the target progression of engine speed n_m_ref from a targettrajectory block for engine speed 20242.

It also receives the target progression of clutch output torquemd_ka_ref from a target trajectory block for clutch output torque 20243.A shifting coordinator block 20241 is responsible for the coordinationof the specifications.

Based on a block diagram, FIG. 3 illustrates the method for determiningtarget trajectories 20242 and 20243 for the clutch output torque and theengine speed that is attained within the arithmetic block for shiftingcoordinator 20241.

In order to calculate the target trajectory for clutch output torquemd_ka_ref, information is provided to block 320 (optimization of targettrajectory parameter) about the driver type, driving situation, andoperating conditions as well as the shifting type and the desired targetvalue for the clutch output torque at the end of shifting phasemd_ka_ziel. The shifting type provides coded information regarding theshifting, for example, 1-2 pull shift (changing from first gear tosecond gear while the engine is driving the vehicle), 4-3 push shift(changing from fourth gear to third gear while the vehicle is drivingthe engine). These input variables are provided to block 320 by shiftingcoordinator 20241 and/or by drive coordinator 202. The calculation ofvalues that the driver type. (e.g., “sporty” or “economy”), the drivingsituation (e.g., mountain driving, winter driving), and the operatingconditions of the assemblies (e.g., temperature of the engine and/orclutch) may be calculated in a conventional manner.

In block 320, parameter vector sigma_k, which establishes thecharacteristics of target trajectory md_ka_ref, is determined from thisinformation. In particular, the elements of vector sigma_k describe theshape of target trajectory md_ka_ref (e.g., linear, PT1-shaped,sinusoid) and its duration (and thus the time interval {ta, te}). Themapping of the input information from block 320 on parameter vectorsigma_k may occur via algebraic calculation specifications,characteristic curves, characteristic maps, fuzzy rules, or neuronalnetworks, optionally also based on a model description of the driveassemblies and the vehicle.

In block 321 (calculation of target trajectory), target trajectorymd_ka_ref is calculated. The output of block 321 is a depiction of thetarget trajectory as a characteristic curve over time interval {ta, te}.In addition to parameter vector sigma_k, the initial value of clutchoutput torque md_ka_start and the desired target value for clutch outputtorque md_ka_ziel at the end of the shift phase are input variables ofblock 321.

In order to calculate the target trajectory for engine speed n_m_ref,information is provided to block 325 (optimization of target trajectoryparameter) regarding the driver type, driving situation, and operatingconditions. Using this information, it determines a parameter vectorsigma_m that establishes the characteristics of target trajectoryn_m_ref. The elements of vector sigma_m in particular describe the shapeof target trajectory n_m_ref (e.g., linear, PT1-shaped, sinusoid). Themapping of the input information of block 325 on parameter vectorsigma_m may occur via algebraic calculation specifications,characteristic curves, characteristic maps, fuzzy rules, or neuronalnetworks, optionally also based on a model description of the driveassemblies and the vehicle.

In block 326 (calculation of target trajectory), target trajectoryn_m_ref is calculated. The output of block 326 is a depiction of thetarget trajectory as a characteristic curve over time interval {ta, te}.In addition to parameter vector sigma_m, the initial value of enginespeed n_m_start, the gradient of engine speed d/dt(n_m_start), thetarget value of engine speed n_m_ziel and its gradient d/dt(n_m_ziel)are input variables of block 326.

The calculation of the target trajectories for the clutch output torqueand/or the engine speed in arithmetic blocks 321 and 326 occurs usingpre-defined mathematical functions such as, for example, a linear,exponential, or sinusoid function.

In an example embodiment of the present invention, spline functions areused to determine the target trajectories for the clutch output torqueand/or the engine speed. For example, the description of the progressionof engine speed n_m_ref is illustrated using spline functions in FIGS.4a and 4 b and the description of target clutch output torque md_ka_refis illustrated; using spline functions in FIGS. 5a and 5 b.

In order to calculate the target trajectory for the engine speed inblock 326, in a first step, the number of the spline base functions(B-splines) and their order as well as their distribution over timeinterval {ta, te} are established. This occurs as a function ofparameter vector sigma_m. Correspondingly, in FIG. 4a, four basefunctions of the order 4 are illustrated. Using these base functions,the target progression of the engine speed is described in such a mannerthat the initial value of engine speed n_m_start, the gradient of enginespeed d/dt(n_m_start), the target value of engine speed n_m_ziel, andits gradient d/dt(n_m_ziel) are satisfied (FIG. 4b). For this purpose, amethod for spline interpolation is used that is described, for example,in de Boor, C.: A Practical Guide to Splines. Applied MathematicalSciences, Vol. 27, Springer-Verlag, New York, 1978. Chapter on splineinterpolation.

In order to calculate the target trajectory for the clutch output torquein block 321, in a first step, the number of spline base functions(B-splines) and their order as well as their distribution over timeinterval {ta, te} are established. This occurs as a function ofparameter vector sigma_k. In the example, it was defined using parametervector sigma_k that the first 70% of the torque build-up may occur in alinear manner. Correspondingly, in FIG. 5a, 6 base functions of theorder 4 are illustrated. Using these base functions, the targetprogression of the clutch output torque is described in such a mannerthat, beginning from an initial value md_ka_start, the torque reachestarget value md_ka_ziel (FIG. 5b).

What is claimed is:
 1. A method for coordinated control of a servoclutch, a vehicle engine and a transmission arranged in a drive train ofa motor vehicle during a change in a gear ratio, comprising the stepsof: establishing temporal progressions of states of the vehicle engineand the servo clutch for the change in the gear ratio; controlling theservo clutch and the vehicle engine during the change in the gear ratioso that the servo clutch and the vehicle engine assume the statesaccording to the temporal progressions established in the establishingsteps; calculating and updating the temporal progressions during adriving operation; and establishing at a beginning of the change in thegear ratio the updated temporal progressions as the progressionsaccording to which control of the servo clutch and the vehicle engineoccurs during the change in the gear ratio.
 2. The method according toclaim 1, wherein the establishing step includes the substeps of:establishing an output speed of the vehicle engine as the state of thevehicle engine; and establishing an output torque of the servo clutch asthe state of the servo clutch.
 3. The method according to claim 1,further comprising the step of calculating during a driving operation ofthe vehicle at least one of: a driver type value representative of abehavior of a driver of the vehicle; a driving situation valuerepresentative of an instantaneous driving situation; an operating statevalue representative of an operating state of at least one element ofthe drive train; and an operating condition value representative of atleast one operating condition of the at least one element of the drivetrain; wherein the temporal progressions are established in theestablishing step in accordance with at least one of the calculatedvalues.
 4. The method according to claim 1, wherein the temporalprogressions are calculated during the driving operation in accordancewith a real-time optimization algorithm.
 5. A device for coordinatedcontrol of a servo clutch, a vehicle engine and a transmission arrangedin a drive train of a motor vehicle during a change in a gear ratio,comprising: a coordination arrangement configured to establish temporalprogressions of states of the vehicle engine and the servo clutch forthe change in the gear ratio, the coordination arrangement furtherconfigured to so that control of the servo clutch and the vehicle engineduring the change in the gear ratio occurs according to the establishedtemporal progressions; wherein the coordination arrangement is furtherconfigured to calculate and update the temporal progressions and toestablish at a beginning of the change in the gear ratio the respectiveupdated progressions as the progressions according to which control ofthe servo clutch and the vehicle engine occurs during the change in thegear ratio.
 6. device according to claim 5, wherein the coordinationarrangement is configured to establish an output speed of the vehicleengine as the state of the vehicle engine and to establish an outputtorque of the servo clutch as the state of the servo clutch.
 7. Thedevice according to claim 5, wherein the coordination arrangement isconfigured to calculate during a driving operation of the vehicle atleast one of: a driver type value representative of a behavior of adriver of the vehicle, a driving situation value representative of aninstantaneous driving situation, an operating state value representativean of operating state of at least one element of the drive train, and anoperating condition value representative of at least one operatingcondition of the at least one element of the drive train; and whereinthe coordination arrangement is configured to determine the temporalprogressions in accordance with at least one calculated value.
 8. Thedevice according to claim 5, wherein the coordination arrangement isconfigured to calculate the temporal progressions during the drivingoperation in accordance with a real-time optimization algorithm.
 9. Adevice for coordinated control of a servo clutch, a vehicle engine and atransmission arranged in a drive train of a motor vehicle during achange in a gear ratio, comprising: coordination means for establishingtemporal progressions of states of the vehicle engine and the servoclutch for the change in gear ratio; wherein control of the servo clutchand the vehicle engine occurs so that the servo clutch and the vehicleengine assume the states according to the established temporalprogressions; and wherein the coordination means is configured tocalculate and update the temporal progressions and to establish at abeginning of the change in the gear ratio the respective updatedprogressions as the progressions according to which control of the servoclutch and the vehicle engine occurs during the change in the gearratio.